The present invention relates to a cation exchange membrane having excellent electrochemical characteristic, cation selective permeability, chemical resistance, heat resistance and mechanical resistance and a process for producing the same. More particularly, it relates to a cation exchange membrane suitable for an electrolysis of an alkali metal halide and a process for producing the same.
Various kinds of cation exchange membranes have been proposed since an electrolysis using an ion exchange membrane has been developed as an important process. However, a cation exchange membrane having satisfactory cation selective permeability, durability and electrical characteristics has not found yet.
The conventional cation exchange membranes have suitable permeation inhibiting property to most of anions, however they have disadvantage of low cation transport number in the case of an aqueous solution of an electrolyte forming hydroxyl ions in comparison with the other case.
This is serious problem since a current efficiency is low when the cation exchange membrane is used in the condition including hydroxyl ions such as a membrane for an electrolysis of sodium chloride.
It has been desired to develop a cation exchange membrane having excellent durability and excellent permeation inhibiting property to anions including hydroxyl ions on the applications of the cation exchange membrane for said purposes.
The inventors have studied from these viewpoints and have found to provide excellent cation exchange membrane.